1. Field of the Invention
This invention relates generally to gas turbine engines and, more particularly, to a method and apparatus for optimally controlling a gas turbine engine.
2. Description of the Prior Art
Modern gas turbine engines have numerous control features which allow for efficient engine operation over a wide range of operating conditions. Because of the interactions between such diverse features as fuel flow, variable fan pitch, variable fan exhaust nozzle areas, etc., a much more complex control system is required if engine efficiency is to be maintained over a widely varying range of ambient conditions and modes of engine operation.
Traditional prior art control systems have relied upon the combination of a number of uncoordinated single closed control loops each of which controlled a particular individual control variable as a function of a single output variable. While the interrelationships between the various individual control loops have increased, the basic design approach of such control systems, combining a number of unrelated closed control loops, has remained the same. The result is that the prior art control systems are inherently unable to fully optimize engine operating efficiency over the entire range of engine operating conditions.
It is, therefore, an object of the present invention to provide a control system for a gas turbine engine in which the control variables are controlled as a function of a plurality of the output variables.
Another object of the present invention is to provide such a control system which automatically optimizes engine operating efficiency over the entire range of operating conditions.
A further object of the present invention is to provide such a control system which automatically accommodates both manufacturing and wear tolerances.
Still another object of the present invention is to provide such a control system in which one or more of the output variables are integrated in order to improve response time.